After I upgraded the target platform of my product from eclipse4.3 to eclipse4.10, my product can't load all bundles in the plugins folder by default anymore, could you please tell me how to configure eclipse4.10 to load all bundles in the plugins folder by default except using org.eclipse.equinox.simpleconfigurator and bundles.info ?

When using eclipse4.3 as target platform, I can configure eclipse to load all bundles by default through configuring the following codes in config.ini:

Generally OSGi only loads bundles that were explicitly specified (i.e., in the osgi.bundles property or via other means like the simpleconfigurator). The update.configurator was a bit of a hack and caused other bad behaviour such as updated or removed bundles being reloaded. The update.configurator behaviour was gutted due to bug 527783.

I am not very sure what do you mean about "How are you building and assembling your app?", before we used a customized config.ini and configured it to load all bundles in the plugins folder.
We'll change our system to generate the bundles.info.

I have looked into that, but as the build features contains exact version of bundles, and If I try to use provinstall with newer version of bundle, it give me error that dependency to old version can not be satisfied, so product could not beresolved.

Actually we are building about 100+ bundles, so it make no sense to install newer feature as it would update much more bundles than the only one, and we have requirement to allow really small patches.

Or is there a way to generate bundle.info property without versions? I remember that with PDE it was possible, but with tycho I didn't found a way to do it.

There I another alternative: the dropins/ folder. It's officially deprecated though still available, and not recommended for a variety of reasons, especially when you have hundreds of bundles -- managing conflicts can be hairy and you may end up with untested combinations. Whereas features let you manage a set of tested combinations.